A method for the rapid disinfection of potable water consumes no chemicals nor relies on the time-consuming action of ultraviolet light. The application of molybdenum sulfide/copper/iron oxide nanoflakes engineered at Stanford University has been demonstrated to inactivate waterborne bacteria in as little as 60 seconds.

The sunlight-activated powder absorbs photons from both ultraviolet and visible light and functions as a semiconductor/metal junction, enabling the photons to release electrons. The latter react with the water, producing hydrogen peroxide and hydroxyl radicals, which kill bacteria by rupturing their protective outer membranes. The hydrogen peroxide and hydroxyl radicals remaining decompose into water and oxygen, and the nanoflakes can be retrieved with magnets for reuse.

During laboratory tests described in Nature Water, the nontoxic powder was added to a 200-ml beaker of room-temperature water contaminated with approximately one million Escherichia coli bacteria/ml. No live bacteria were detected after the water was exposed to natural sunlight for one minute.

The researchers envision diverse uses for this disinfection agent, such as in the provision of safe drinking water in rural areas as well as in centralized water treatment plants.